Simple probing is the most widely-used initial treatment for NLDO in infancy. Two differing approaches to simple probing have been most often been used, immediate office probing (early probing-generally after 6 months of age), and medical management (episodic antibiotic drops with massage of the lacrimal sac) until 9-13 months of age followed by probing under general anesthesia (late probing). The possible advantages of early probing are the avoidance of general anesthesia, immediate resolution of symptoms, lesser cost, and prevention of fibrosis from inflammation in the nasolacrimal duct. The advantages of late probing include more comfort with the procedure and the avoidance of the procedure completely. Both early and late probing approaches are usually successful for treatment of NLDO in patients under 2 years of age, with reported success proportions varying from between 54% to 98%. Although a number of studies have found that probing was highly successful and without an age-related decline until at least 4 years of age and beyond, there is a suspicion among other clinicians of a clinically-important decline in the success proportions among progressively older age groups of preschool children. A large prospective interventional case series might help to clarify whether there is an age-related decline in success.